The present invention relates generally to cotton harvesters and more specifically to an overload sensor for the input drive of a cotton harvester.
A typical cotton harvester includes a plurality of individual picking units, each with upright picker bar drums and doffer columns for removing cotton from a row of cotton plants and directing it to a conveyor system. The picker drums and doffer columns are driven by a transmission operably connected by a universal joint to one end of a drive shaft. The opposite end of the drive shaft is carried by a shaft support pivotally connected to the harvester frame about a pivotal axis generally parallel to the drive shaft axis. A pulley is mounted on the drive shaft adjacent the support and is driven by a belt trained around a main drive pulley. A bolt having an adjusting nut is connected between the frame and the shaft support. The tension in the belt is adjusted by turning the adjusting nut which pivots the shaft support to move the drive shaft pulley toward or away from the main drive pulley. The above-described drive arrangement is shown, for example, on the John Deere 9900 Cotton Picker. A slip clutch is provided, either at the input to the transmission or at the drive shaft pulley. When free running operation of the picking unit is prevented, the slip clutch associated with the drive shaft will slip to remove drive from the unit. Overloads can occur when a unit plugs with cotton, a unit encounters an obstruction or dirt builds up within a unit. Cold or stiff grease can also cause an overload of the input drive shaft.
Although the slip clutch associated with the drive shaft provides protection from overloads, it has not been entirely satisfactory. The slip clutch must not begin to slip until the loading on the drive shaft exceeds the maximum encountered during normal operation of the picker unit. Therefore, the operator will have no indication that a problem is developing until the clutch actually slips. The operator may not hear the clutch immediately when it begins to slip because of both the level of noise associated with the harvester during the picking of the cotton and the improved sound isolation of the cab from the remainder of the harvester. As a result, the overload condition may not be detected immediately and may cause machine damage or loss of cotton. The longer the overload condition remains undetected, the more likely it is that it will worsen and result in increased maintenance time and decreased productivity.
It is therefore an object of the present invention to provide a device for the early detection of an overload or an impending overload condition in a cotton harvester row unit.
It is another object of the present invention to provide a device for monitoring the loading of the drive for a cotton harvester row unit and providing a warning when the loading exceeds a preselected limit. It is a further object to provide such a device which is relatively simple and inexpensive to manufacture and which is easily adjustable.
It is still another object of the invention to provide a relatively simple and inexpensive device for the drive shaft of a cotton harvester row unit which functions both as an adjustable belt tightener and as a shaft overload sensor. It is another object to provide such a device which provides a warning when the sensed load increases beyond a preselected limit and which includes an adjustment for setting the desired load limit.
It is yet another object of the invention to provide a device for monitoring the loading on a slip clutch-protected cotton harvester row unit which provides a signal to the operator of the harvester to warn him of an impending overload condition before the slip clutch begins to slip.
A support assembly pivotally connected to the frame of the cotton harvester carries a row unit drive shaft adjacent a first pulley operably connected by a belt to a main drive pulley. An eyebolt is connected at its eye end to the support assembly and at its threaded end to a sensor arm by a nut. The sensor arm is biased in the direction to cause the support assembly to tension the belt between the drive and driven pulleys. The spring rate of the spring assembly is preloaded to balance the belt tension required to drive the row unit under normal conditions. When the row unit is loaded beyond normal conditions, the preload of the spring is overcome and the sensor arm moves. Sensor arm movement activates a switch which lights a lamp to alert the operator that an overload condition exists. Belt tension is adjusted by turning the nut threaded into the eyebolt.
When the row unit is operating under normal load conditions, the spring assembly maintains the switch in the off condition. If an overload occurs in the unit, the tension in the drive belt increases and the sensor arm moves against the bias of the spring assembly to activate the switch and provide an early warning to the operator. The operator is then able to take immediate action to remedy the problem causing the overload. The device is relatively simple and inexpensive, and provides for easy adjustment of both belt tension and overload sensitivity. Sensitivity is set so that the operator is warned of an impending overload condition prior to operation of the slip clutch.
These and other objects, features and advantages will become apparent to those skilled in the art upon a reading of the following description of the preferred embodiment taken with the drawings.